In recent years, an electrically driven vehicle such as an electric vehicle and a hybrid car has attracted attention as an environmentally friendly vehicle. The electrically driven vehicle is equipped with a battery that is capable of charging driving power from an external power supply. As a method of supplying power for charging, a plug-in type power supply method in which a power-supply-side power source outlet and a charging inlet of a vehicle are connected to each other with a cable, and a non-contact type power supply method not using the cable has been disclosed.
As a technology related to the non-contact type power supply method in the related art, for example, a non-contact power supply system disclosed in JPA-2010-93957 may be exemplified. In this technology in the related art, a power transmission is performed with an electromagnetic field interposed between a primary coil and a secondary coil. In the non-contact power supply system disclosed in JP-A-2010-93957, power from an external facility equipped with an AC power supply is converted into high-frequency power by, a high-frequency power driver and then is supplied to the primary coil. In the secondary coil provided at the bottom of a vehicle, a current flows due to an electromagnetic coupling, and thereby power is supplied to the secondary coil from the opposite primary coil.
In the related art, as described above, since power is transmitted with an electromagnetic field interposed between the primary coil disposed in the vicinity of the ground and the secondary coil disposed at the bottom of the vehicle, during a power supply operation, there is a concern in that when a person is in the vicinity of the primary coil or the secondary coil, the human body may be affected by the electromagnetic field.
Specifically, in the related art, when doors of a vehicle are locked, a charging starting request signal is transmitted to an external apparatus of the vehicle, and then a charging operation is started. When the charging operation is started at this timing, there is a possibility that a person may be in the vicinity of the vehicle, and the human body may be affected by the electromagnetic field.
In recent years, an electrically driven vehicle such as an electric vehicle and a hybrid car has attracted attention as an environmentally friendly vehicle. The electrically driven vehicle is equipped with a battery that is capable of charging driving power from an external power supply. As a method of supplying power for charging, a plug-in type power supply method in which a power-supply-side power source outlet and a charging inlet of a vehicle are connected to each other with a charging cable, and a non-contact type power supply method not using a power supply cable has been disclosed.
As a technology related to the non-contact type power supply method in the related art, for example, a non-contact power charge system disclosed in JPA-2008-87733 may be exemplified. This technology in the related art performs a power transmission via a magnetic field. In the non-contact power charge system disclosed in JP-A-2008-87733, power from an external facility equipped with an AC power supply is converted into high-frequency power by a high-frequency power driver and is supplied to the primary coil, and the primary coil transmits high-frequency power to a vehicle in which the secondary coil is mounted by electromagnetic induction.
In the technology in the related art, as described above, since power is transmitted with an electromagnetic field interposed between the primary coil disposed in the vicinity of the ground and the secondary coil disposed at the bottom of the vehicle, during a charging operation, when a person is in the vicinity of the primary coil or the secondary coil, or a small animal is on a box covering a primary self-resonance coil, the human body or animal may be affected by the electromagnetic field.
The electrically driven vehicle such as the electric vehicle and the hybrid car is equipped with a battery that is capable of charging driving power from an external power supply. As a method of supplying power for charging, a plug-in type power supply device in which a power-supply-side power source outlet and a charging inlet of a vehicle are connected to each other with a cable, and a non-contact type power supply device not using the cable has been disclosed.
As the non-contact type power supply device, a type using electromagnetic induction may be exemplified. In the type using electromagnetic induction, in order to provide a countermeasure against a metallic foreign body generating heat due to a high-frequency magnetic field and reaching a high temperature, and thereby stability of a product possibly not being secured, a device that automatically stops the power supply in a case where the power supply device reaches a high temperature is provided. In addition, a transmission efficiency is detected during the power supply, and whether or not a foreign body such as an object or a person approaches is detected during the power supply based on the transmission efficiency (for example, JP-A-2010-119246).
In addition, when the non-contact power supply is used for charging a vehicle during parking, a positional deviation between a power transmitting section and a power receiving section is different each time because a deviation in a parking position is present. Therefore, in JP-A-2006-345588, transmission efficiency between power transmission and power reception is used, and a relative position is adjusted to improve the transmission efficiency.
In JP-A-2010-119246, it is difficult to discriminate between an efficiency deterioration due to a foreign body and an efficiency deterioration due to a positional deviation. Therefore, the efficiency deterioration due to the positional deviation may be erroneously determined as the efficiency deterioration due to the foreign body, and the power supply may be stopped.
In consideration of this, a technology in which the power transmission is performed while changing a frequency in minuscule power, an efficient frequency characteristic is detected, the efficiency deterioration due to the foreign body and the efficiency deterioration due to the positional deviation of the coils are discriminated based on the detection result, and the coil position is adjusted using a coil position adjusting section may be considered. In addition, JP-A-2006-345588 discloses means for making the primary coil move in order for the efficiency of the power supply coil to be a maximum, and for making the efficiency deterioration due to the positional deviation a minimum. However, this means needing a circuit that changes a frequency of supplying power or a mechanism that allows a coil to physically move. Therefore, a manufacturing cost increases, but also it is difficult to detect whether or not the foreign body is present in a case where the foreign body intrudes between the coils during power supply.